What does microcytic rbcs in urinalysis mean protein and wbcs were normal ?

Likely mechanical,,,: This likely comes from a mechanical issue where blood cells pass through the glomerulus and tubules and get damaged, so they get dysmorphic features, but they usually are doughnut shaped, not microcytic. This happens in glomerulonephritis or inflammation from infection or autoimmune diseases. It can also be due to a bleeding/hemolytic issue from heart valve, etc. Or ureter issue (stones, etc.).